tonight, president obama's national security adviser is flying home from afghanistan and empty-handed. susan rice's mission was to persuade afghan president hamid karzai to sign a new security agreement that will keep some u.s. troops in afghanistan after the nato combat mission ends after next year. major gar marrett's at the white house. >> reporter: the white house says president karzai holds in his hans the future security of his country and the promise of $8 billion in annual u.s. aid. that hand currently will not sient security agreement the u.s. thought was sealed and delivered. national security adviser susan rice's face-to-face meeting with the afghan president produced nothing but frustration. >> what i said to the president is we would have no choice. we would be compelled by necessity-- not by our preference-- to have to begin to plan for the prospect that we will not be able to keep our troops here because they will not be invited because the b.s.a. will not have been signed. >> reporter: the b.s.a., or bilateral security agreement, sets the rules for any u.s. troops that